In recent, as infants or children are encouraged to play out of doors, a case is increased that artificial turf is installed in schools or apartments. Normal method for installing the artificial turf is as follows. The artificial turf is laid down on ready-mixed concrete or tramped rubbles, and thereafter silica sands are scattered among the artificial turfs to secure it. Then, the filler material is laid down on the silica sands, thereby making the artificial turfs buried in the filler material.
For the filler material, rubber chips are generally used. The rubber chips are pulverized by sun light etc. to produce smashed powders. There is a problem that the smashed powders deposited on the floor fly around to enter the respiratory organs of the infants or children, thereby damaging their health. Furthermore, since the rubber chips generate much frictional heat and also have a low moisture content, a problem is present that when users slip very high risk of burning appears.